Ice-marginal lava flow

An ice marginal lava flow is a phenomenon associated with glaciovolcanism. Glaciovolcanism is the study of volcano and ice interaction, so essentially any and all volcanic activity that interacts with any sort of ice formation The science of glaciovolcanism relatively young in age because, to study it, people must overcome hostile environments. While young, the science of glaciovolcanism can give us clues to in order to reconstruct volcanoes  from the past and answer questions regarding whether or not ice was present in a certain area, the thickness of the ice, the surface elevation of the ice sheet and finally the structure of the ice sheet. Glaciovolcanism is increasingly important for volcanic hazard awareness and preparedness, studying the Pleistocene climate record, possible relationships between deglaciation and volcanism, and finally possible Martian geoscience research.  

There are three subdivisions of glaciovolcanism: supraglacial volcanism, subglacial volcanism, and ice-marginal volcanism.  Supraglacial volcanism is the direct eruption of lava onto a glacier. Subglacial volcanism is the eruption of a volcano beneath of a glacier. Finally, ice-marginal volcanism is a volcanic eruption that does not erupt above or below a glacier, but the lava flow comes into direct contact with a glacier or large ice sheet's margins. Initially, the lava  flow is like any other but when the lava reaches the margins of an ice sheet, the front of the lava flow cools very quickly and thus, forms a barrier (Figure 1). Behind this barrier, the lava begins to pool, ceasing the contact between the hot lava and cold ice. The barrier is left behind as the ice retreats, leaving a thick lava front, which is just a large, steep, and unstable cliff face.

The Barrier

A fantastic example of a natural lava dam formed from an ice-marginal lava flow is a phenomenon aptly named “The Barrier” in the Garibaldi Volcanic Belt. The Garibaldi Volcanic Belt is located in the northern part of  the Cascade Ranges. The Barrier was formed when about 13,000 years ago Mount Price, one of the 13 volcanoes that make up the Garibaldi volcanic belt, erupted and sent a lava flow down Rubble Creek Valley and met the Cordilleran Ice Sheet

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